Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/nios2/kernel/misaligned.c |
| 3 | * |
| 4 | * basic emulation for mis-aligned accesses on the NIOS II cpu |
| 5 | * modelled after the version for arm in arm/alignment.c |
| 6 | * |
| 7 | * Brad Parker <brad@heeltoe.com> |
| 8 | * Copyright (C) 2010 Ambient Corporation |
| 9 | * Copyright (c) 2010 Altera Corporation, San Jose, California, USA. |
| 10 | * Copyright (c) 2010 Arrow Electronics, Inc. |
| 11 | * |
| 12 | * This file is subject to the terms and conditions of the GNU General |
| 13 | * Public License. See the file COPYING in the main directory of |
| 14 | * this archive for more details. |
| 15 | */ |
| 16 | |
| 17 | #include <linux/errno.h> |
| 18 | #include <linux/string.h> |
| 19 | #include <linux/proc_fs.h> |
| 20 | #include <linux/init.h> |
| 21 | #include <linux/sched.h> |
| 22 | #include <linux/uaccess.h> |
| 23 | #include <linux/seq_file.h> |
| 24 | |
| 25 | #include <asm/traps.h> |
| 26 | #include <asm/unaligned.h> |
| 27 | |
| 28 | /* instructions we emulate */ |
| 29 | #define INST_LDHU 0x0b |
| 30 | #define INST_STH 0x0d |
| 31 | #define INST_LDH 0x0f |
| 32 | #define INST_STW 0x15 |
| 33 | #define INST_LDW 0x17 |
| 34 | |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 35 | static unsigned int ma_usermode; |
| 36 | #define UM_WARN 0x01 |
| 37 | #define UM_FIXUP 0x02 |
| 38 | #define UM_SIGNAL 0x04 |
| 39 | #define KM_WARN 0x08 |
| 40 | |
| 41 | /* see arch/nios2/include/asm/ptrace.h */ |
| 42 | static u8 sys_stack_frame_reg_offset[] = { |
| 43 | /* struct pt_regs */ |
| 44 | 8, 9, 10, 11, 12, 13, 14, 15, 1, 2, 3, 4, 5, 6, 7, 0, |
| 45 | /* struct switch_stack */ |
| 46 | 16, 17, 18, 19, 20, 21, 22, 23, 0, 0, 0, 0, 0, 0, 0, 0 |
| 47 | }; |
| 48 | |
| 49 | static int reg_offsets[32]; |
| 50 | |
| 51 | static inline u32 get_reg_val(struct pt_regs *fp, int reg) |
| 52 | { |
| 53 | u8 *p = ((u8 *)fp) + reg_offsets[reg]; |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 54 | return *(u32 *)p; |
| 55 | } |
| 56 | |
| 57 | static inline void put_reg_val(struct pt_regs *fp, int reg, u32 val) |
| 58 | { |
| 59 | u8 *p = ((u8 *)fp) + reg_offsets[reg]; |
| 60 | *(u32 *)p = val; |
| 61 | } |
| 62 | |
| 63 | /* |
| 64 | * (mis)alignment handler |
| 65 | */ |
| 66 | asmlinkage void handle_unaligned_c(struct pt_regs *fp, int cause) |
| 67 | { |
| 68 | u32 isn, addr, val; |
| 69 | int in_kernel; |
| 70 | u8 a, b, d0, d1, d2, d3; |
Bernd Weiberg | db5a7e5 | 2015-09-04 17:03:03 +0800 | [diff] [blame] | 71 | s16 imm16; |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 72 | unsigned int fault; |
| 73 | |
| 74 | /* back up one instruction */ |
| 75 | fp->ea -= 4; |
| 76 | |
| 77 | if (fixup_exception(fp)) { |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 78 | return; |
| 79 | } |
| 80 | |
| 81 | in_kernel = !user_mode(fp); |
| 82 | |
| 83 | isn = *(unsigned long *)(fp->ea); |
| 84 | |
| 85 | fault = 0; |
| 86 | |
| 87 | /* do fixup if in kernel or mode turned on */ |
| 88 | if (in_kernel || (ma_usermode & UM_FIXUP)) { |
| 89 | /* decompose instruction */ |
| 90 | a = (isn >> 27) & 0x1f; |
| 91 | b = (isn >> 22) & 0x1f; |
| 92 | imm16 = (isn >> 6) & 0xffff; |
| 93 | addr = get_reg_val(fp, a) + imm16; |
| 94 | |
| 95 | /* do fixup to saved registers */ |
| 96 | switch (isn & 0x3f) { |
| 97 | case INST_LDHU: |
| 98 | fault |= __get_user(d0, (u8 *)(addr+0)); |
| 99 | fault |= __get_user(d1, (u8 *)(addr+1)); |
| 100 | val = (d1 << 8) | d0; |
| 101 | put_reg_val(fp, b, val); |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 102 | break; |
| 103 | case INST_STH: |
| 104 | val = get_reg_val(fp, b); |
| 105 | d1 = val >> 8; |
| 106 | d0 = val >> 0; |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 107 | if (in_kernel) { |
| 108 | *(u8 *)(addr+0) = d0; |
| 109 | *(u8 *)(addr+1) = d1; |
| 110 | } else { |
| 111 | fault |= __put_user(d0, (u8 *)(addr+0)); |
| 112 | fault |= __put_user(d1, (u8 *)(addr+1)); |
| 113 | } |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 114 | break; |
| 115 | case INST_LDH: |
| 116 | fault |= __get_user(d0, (u8 *)(addr+0)); |
| 117 | fault |= __get_user(d1, (u8 *)(addr+1)); |
| 118 | val = (short)((d1 << 8) | d0); |
| 119 | put_reg_val(fp, b, val); |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 120 | break; |
| 121 | case INST_STW: |
| 122 | val = get_reg_val(fp, b); |
| 123 | d3 = val >> 24; |
| 124 | d2 = val >> 16; |
| 125 | d1 = val >> 8; |
| 126 | d0 = val >> 0; |
| 127 | if (in_kernel) { |
| 128 | *(u8 *)(addr+0) = d0; |
| 129 | *(u8 *)(addr+1) = d1; |
| 130 | *(u8 *)(addr+2) = d2; |
| 131 | *(u8 *)(addr+3) = d3; |
| 132 | } else { |
| 133 | fault |= __put_user(d0, (u8 *)(addr+0)); |
| 134 | fault |= __put_user(d1, (u8 *)(addr+1)); |
| 135 | fault |= __put_user(d2, (u8 *)(addr+2)); |
| 136 | fault |= __put_user(d3, (u8 *)(addr+3)); |
| 137 | } |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 138 | break; |
| 139 | case INST_LDW: |
| 140 | fault |= __get_user(d0, (u8 *)(addr+0)); |
| 141 | fault |= __get_user(d1, (u8 *)(addr+1)); |
| 142 | fault |= __get_user(d2, (u8 *)(addr+2)); |
| 143 | fault |= __get_user(d3, (u8 *)(addr+3)); |
| 144 | val = (d3 << 24) | (d2 << 16) | (d1 << 8) | d0; |
| 145 | put_reg_val(fp, b, val); |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 146 | break; |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | addr = RDCTL(CTL_BADADDR); |
| 151 | cause >>= 2; |
| 152 | |
| 153 | if (fault) { |
| 154 | if (in_kernel) { |
| 155 | pr_err("fault during kernel misaligned fixup @ %#lx; addr 0x%08x; isn=0x%08x\n", |
| 156 | fp->ea, (unsigned int)addr, |
| 157 | (unsigned int)isn); |
| 158 | } else { |
| 159 | pr_err("fault during user misaligned fixup @ %#lx; isn=%08x addr=0x%08x sp=0x%08lx pid=%d\n", |
| 160 | fp->ea, |
| 161 | (unsigned int)isn, addr, fp->sp, |
| 162 | current->pid); |
| 163 | |
| 164 | _exception(SIGSEGV, fp, SEGV_MAPERR, fp->ea); |
| 165 | return; |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | /* |
| 170 | * kernel mode - |
| 171 | * note exception and skip bad instruction (return) |
| 172 | */ |
| 173 | if (in_kernel) { |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 174 | fp->ea += 4; |
| 175 | |
| 176 | if (ma_usermode & KM_WARN) { |
| 177 | pr_err("kernel unaligned access @ %#lx; BADADDR 0x%08x; cause=%d, isn=0x%08x\n", |
| 178 | fp->ea, |
| 179 | (unsigned int)addr, cause, |
| 180 | (unsigned int)isn); |
| 181 | /* show_regs(fp); */ |
| 182 | } |
| 183 | |
| 184 | return; |
| 185 | } |
| 186 | |
Ley Foon Tan | 82ed08d | 2014-11-06 15:19:38 +0800 | [diff] [blame] | 187 | /* |
| 188 | * user mode - |
| 189 | * possibly warn, |
| 190 | * possibly send SIGBUS signal to process |
| 191 | */ |
| 192 | if (ma_usermode & UM_WARN) { |
| 193 | pr_err("user unaligned access @ %#lx; isn=0x%08lx ea=0x%08lx ra=0x%08lx sp=0x%08lx\n", |
| 194 | (unsigned long)addr, (unsigned long)isn, |
| 195 | fp->ea, fp->ra, fp->sp); |
| 196 | } |
| 197 | |
| 198 | if (ma_usermode & UM_SIGNAL) |
| 199 | _exception(SIGBUS, fp, BUS_ADRALN, fp->ea); |
| 200 | else |
| 201 | fp->ea += 4; /* else advance */ |
| 202 | } |
| 203 | |
| 204 | static void __init misaligned_calc_reg_offsets(void) |
| 205 | { |
| 206 | int i, r, offset; |
| 207 | |
| 208 | /* pre-calc offsets of registers on sys call stack frame */ |
| 209 | offset = 0; |
| 210 | |
| 211 | /* struct pt_regs */ |
| 212 | for (i = 0; i < 16; i++) { |
| 213 | r = sys_stack_frame_reg_offset[i]; |
| 214 | reg_offsets[r] = offset; |
| 215 | offset += 4; |
| 216 | } |
| 217 | |
| 218 | /* struct switch_stack */ |
| 219 | offset = -sizeof(struct switch_stack); |
| 220 | for (i = 16; i < 32; i++) { |
| 221 | r = sys_stack_frame_reg_offset[i]; |
| 222 | reg_offsets[r] = offset; |
| 223 | offset += 4; |
| 224 | } |
| 225 | } |
| 226 | |
| 227 | |
| 228 | static int __init misaligned_init(void) |
| 229 | { |
| 230 | /* default mode - silent fix */ |
| 231 | ma_usermode = UM_FIXUP | KM_WARN; |
| 232 | |
| 233 | misaligned_calc_reg_offsets(); |
| 234 | |
| 235 | return 0; |
| 236 | } |
| 237 | |
| 238 | fs_initcall(misaligned_init); |